What the future holds for the longevity and efficiency of solar panels

Defying expectations, 32-year-old solar panels in the Phébus 1 plant in Lyon, France’s oldest grid-connected PV system, are still going strong.

Recent tests done by the French photovoltaics group Hespul showed that the panels installed in 1992 still operate at an astonishing 79.5% efficiency.

This remarkable endurance dispels doubts about the durability of older PV technology and strengthens solar’s economic potential.

In this blog, we look at the long-term field performance of PV panels and the advancements in solar technology have led to the development of highly efficient solar panels, which promise even greater energy conversion rates and longer lifespans.

Understanding Solar Panel Efficiency

What is solar panel energy efficiency?

Solar panel energy efficiency refers to the ability of a solar panel to convert sunlight into usable electricity. It is commonly expressed as a percentage, with higher percentages indicating greater efficiency. The efficiency of a solar panel is influenced by the quality of the photovoltaic (PV) cells, the design of the panel, and the materials used.

How efficient are solar panels?

The efficiency of solar panels has seen remarkable improvements over the years. Modern solar panels can achieve efficiencies of up to 22.8%, with the average efficiency around 19-22%. However, it’s important to note that solar panel efficiency can vary based on factors such as temperature, sunlight exposure, and the overall quality of the panel. These advancements in efficiency mean that today’s solar panels are more capable than ever of converting solar radiation into usable electricity.

How long should solar panels last?

PV panels are built to exceed a 25-year service life, which is why panels from as far back as the 1990s are still meeting their performance targets. Because their components are stationary, they are less susceptible to internal damage and remain resilient against severe weather.

That said, even the most durable panels aren’t immune to time. Their energy output gradually tapers off at a rate of about 0.5–0.8% per year. This means a typical high-quality panel can only produce 90% of its original capacity after 20 years.

Manufacturers often provide product and performance guarantees to address this issue, ensuring that efficiency will not dip below 80% before the warranty ends. This baseline expectation helps protect grid-scale solar investments and makes financial forecasts more reliable. 

What affects solar panels’ longevity?

Solar panels gradually lose efficiency as their components break down from natural wear and tear. This decline, called degradation rate, depends on the following factors:

Materials used

Monocrystalline panels, made from pure silicon, last the longest and are known for their highly efficient single-crystal structure that absorbs light and converts energy efficiently. This slows degradation to a rate of 0.3% to 0.5% annually. These panels can still operate at 80% to 92% of their initial efficiency even after 25 years.

Polycrystalline cells are more cost-effective than monocrystalline and also last a long time, usually for 25 to 30 years. They decline slightly faster at 0.79% to 1.67% annually but remain a solid choice for large-scale solar projects.

Thin-film solar panels (including amorphous silicon types) are cheaper and easier to manufacture but have the shortest lifespan. They last 10 to 20 years and tend to be more vulnerable to environmental stresses.

Climate and environmental factors

Extreme weather events like hailstorms, strong winds, and heavy snowfall can physically damage panels. For instance, tree branches and large hailstones might crack a panel’s anti-reflective glass during severe windstorms. Heavy snowfall can also threaten a panel’s structural integrity. This is why utility-scale PV panels must undergo rigorous testing and certification to withstand harsh conditions and ensure uninterrupted operation.

Installation quality and maintenance

PV panel systems that adhere to high-quality deployment and maintenance protocols may last longer. Best practices include:

• Proper site preparation (including land clearing, grading, and soil compaction).

• Using durable mounting systems to protect panels from adverse conditions.

• Routine inspections to identify and address loose connections, damaged cables, or debris buildup.

• Using advanced monitoring systems for real-time panel performance tracking and early damage detection.

Light-Induced Degradation (LID)

This phenomenon primarily affects crystalline silicon solar cells, especially those doped with boron. When exposed to sunlight, these cells can experience an initial efficiency drop of 6% to 8% within the first decade. While newer N-type cells are less susceptible, LID remains a concern for many existing installations.

Potential-Induced Degradation (PID)

PID occurs due to voltage differences between the solar cell and other components, creating an imbalance that triggers ion migration and reduces the panel’s ability to convert sunlight into electricity. Environmental factors, panel design, and materials influence PID severity.

How long have solar panels been proven to last?

Decades of research and real-world data from various regions and climates consistently affirm that solar panels can reliably produce energy for decades, often surpassing initial manufacturer projections.

• As mentioned, French solar modules installed in 1992 continue to deliver 79.5% of their initial power output after 31 years, a notably low annual degradation rate of just 0.66% over three decades.

• Now over 40 years old, the TISO-10 PV system in Switzerland (operational since 1982) shows similar longevity. While PV panels in the project used different encapsulant additives from three manufacturers, their overall power output loss stayed within expected limits.

• On a larger scale, NREL (U.S. National Renewable Energy Laboratory) analyzed over 7.2 GW of solar capacity (1,700 sites) across the United States. The median performance drop stayed at 0.75% per year, even in the face of extreme weather conditions.

Will solar panel efficiency and longevity keep improving?

Solar panels are already quite durable, but researchers are still pushing the boundaries to develop even more efficient and resilient systems. These efforts can further extend PV lifespans in the future:

Low degradation panels

PV manufacturers are focusing on technologies that slow down the rate of efficiency loss over time. Passivated Emitter and Rear Contact (PERC) solar cells, for example, feature an additional layer on the rear side that reflects unconverted sunlight back into the cell. This boosts energy conversion while keeping the panels cooler to reduce temperature-related performance losses and degradation. These advancements are crucial for developing efficient panels that maintain high performance over extended periods.

Perovskite-on-silicon tandem cells

Oxford PV’s proprietary 72-cell perovskite modules produce up to 20% more energy than standard silicon panels. This innovation lowers electricity costs and generates more power from the same area to optimize land use. These panels also exhibit an exceptional 24.5% module efficiency, far superior to traditional silicon-based solutions. Although this is increasing electricity generation, the hope is that the lifespan of these modules matches or exceeds those currently on the market. These innovations are pushing the boundaries of solar cell efficiency, leading to more effective solar panels.

Research on backsheet technology

The DuraMAT consortium is actively advancing research on PV backsheets, vital layers that shield electrical components from environmental and mechanical damage. One of their latest projects pits newer non-fluorinated, co-extruded backsheet materials against traditional market benchmarks to see if they are more durable. By monitoring how these new backsheets degrade over time under different conditions, DuraMAT aims to create better lifespan prediction models for the industry.

With these advancements, PV panels should last even longer, making utility-scale PV farms financially viable and solar technology truly sustainable.